Rotary compressor



Jan 6, 1931. T. w. NICHOLS ROTARY COMPRESSOR Filed April 16, 1930 FIG].

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INVENTOR. Thomaswinfisrmcholls. littering QM Patented Jan. 7 6, 1931 UNITED STATES PATENT OFFICE I THOMAS WINTER.NIGHOLS, OF LONDON, ENGLAND ROTARY COMPRESSOR Application. filed April 16,1930, Serial No. 444,8 07 a1iu in creat Britain January 3,1929.

This invention relates to rotary air compressors or pumps oi the kind comprising a casing within which is a rotor revoluble eccen-' trically within a cylindrical casing and hav ing teeth adaptedto mesh with a revoluble ring of teeth. Insuch air pumps it is known to provide the rotor with radially slidable'packing vanes to increase the efficiency of the same but owing to-the very high speed at which these compressors are run, difficulties have been experienced in theme of such slidable packing vanes on account of the friction created due to the pressure of their ends on the inside 0f the casing wall. To overcome or reduce this friction in some compressors a false rotor is fitted which is carried round in the same direction as the internal rotor by the frictional contact of the vanes, but as the compressed gas or air has to be delivered through this false rotor, abnormal clearance is set up entailing a very poor efiiciency, reduced output, and considerable loss of the motive energy, owing to the work done on the air or gas which is compressed into these clearance spaces, which is not delivered, but is carried round to re-expand again on the suction or delivery side of the pump.

In my improved machine the rotor positively drives the external ring of teeth, the spaces between the teeth of which are so formed that a tooth of the rotor in complete mesh with the ring will entirely fill its space in thering except for the very small clearance necessary to allow proper action of the gearing.

In the annexed drawings Fig. 1 is a transverse vertical section of my improved compressor.

Fig. 2 is a' longitudinal sectional elevation thereof.

In the drawings 1 indicates the rotor, 2 the revoluble toothed ring driven by the rotor, 3'the driving shaft on whichthe rotor is keyed, 4; the pump casing, 5 the inlet of the pump and 6 the outlet.

' In my improved pump I provide the rotor with packing vanes 7 slidable by centrifugal force in substantially radial slots formed in the rotor 1. These slots and packing vanes may be provided in each space between the teeth 9 orv in alternate or other spaces and are situated for instance close up behind each tooth with respect' to the direction of rotation ofthe rotor as shown in Fig. 1 of the drawing and thesehousings and consequently the vanes, instead of being strictly radial can be arranged at a suitable angle so that the ends of the vanes will meetthe ring 2 as nearly as possible at rightangles to the surface of contact. The outer edges of these packing vanes arefconstantly maintained against the inner circumference 10 ofthe ring during the working of the pump by centrifugal force. i o

The rotor and the ring being in reality internal gears," the'difference of velocity between them is comparatively small, although they may be revolving at a very high speed.

For instance assuming thatthe rotor, which is the driver has 12 teeth as illustrated, is running at two thousand revolutions per minutethe ring having 1a spaces would be runningata speedof 1714 revolutions per minute, so that the relative speed of movement of the packing vanes over the internal surface of the ring would only be at the rate of 286 revolutions 'per minute, and therefore not likely to give trouble through undue friction causing-overheating or "scoring.

The vanes 7 areas shown'in'Fig. 2 of the drawing somewhat longer than the spaces 11 s between the teeth 12 of the ringQ and consequently are prevented from.moving radially into the said spaces by engaging the ends 13' of the inner face 10 of the outer ring as shown in Fig. 2 of said drawing.

1 In the construction illustrated each packing vane 7 shuts off one tooth 9 and one space, in. the rotorl and thering 2, respectively, while the teeth on meshing compress the air and discharge into the delivery chamber 14 of the pump.

The vanes 7 may be each formed of .two or more independently slidable plates as shown in Fig. 1 of the drawing.

Two or more annular packing spaces are provided at each end of the rotor and ring which are designed for the reception of packingrings 15, 16' to prevent leakage of.

air under pressure as shown in Fig. 2 of the drawing.

The springs '18 are carried in recesses in the packing ring 15. this ring being prevented 5 from revolving by means of stop screws 19 in the end cover. The packing rings 16 are arranged in a similar manner and held by screws 22, 1 a

In an alternative method there may be inscrted in the annular packing space between the packing ring 20 and the end covers ofthe pump a helical spring 21.

The ring 52 rotates within a cylindrical por tion 23 of the casing 1 with which the inlet i chamber 24 and the delivery chamber 1.4 l

communicate, the casing being closed at its ends by end 'overs25 and 26. v

"lhcse end covers are provided with in- 1 wardlv directed concentric bosses 27 within 20 which are eccentric-ally arranged the roller bearings 28 for the driving shaft on which the rotor 1 is keyed; the rollers run in hardened steel bushes 31. i The revoluble ring 2 is formed of two end cheeks 29 between which the teeth 12 are mounted means of screws 30 01 in any 7 other convenient way the ball bearings 17 on which the ring rotates being arranged in re cesses of theend cheeks 29 and surrounding an the bosses 27 as shown in Fig. 2 of the draw:

mg, n p j c What I claim as 'myinvention and desire to secure by Letters Patent of the United States is: L. I g An air compressorcomprising a casing formed with opposed inlet and outlet, a a cylindrical ring snugly fitted within the casing and having tooth-shaped slot-s disposed longitudinally therein, at equi distances 40 apart and extending entirely therethrough, a rotor eccentrically. movable within the ring and having equi-distanced gear teeth for engagement in the slots in said ring, andpacking vanes mounted in the rotor contiguous to its teeth tangentially to its axis andic ontacting by centrifugal force with the ring at substantially right angles to the meeting points of said ring and vanes, the slots and teeth being atless axial length than; the

vanes. i 1 THOMAS'WTNTER NICHQLS. 

